1. Field of the Invention
The present invention relates to a portable terminal apparatus with a telephone function, such as a portable telephone.
2. Description of the Related Art
In recent years, portable terminal apparati such as portable telephones are remarkably developing, and it is demanded that they become further multifunctional, miniaturized and lightweight.
The portable telephone in recent years has a speaker built therein to hear a voice without putting one's ear on the portable telephone, and the speaker now has high performance to output music of sound quality. Japanese Patent Laid-Open No. 2002-345084 discloses an example of the speaker built into the portable telephone. The speaker disclosed in Japanese Patent Laid-Open No. 2002-345084 has a front face rim of its sound producing section surrounded by a circular gasket and a connector mounted on its backside, where assembly man-hours are reduced.
As a part of multifunctionality of a portable terminal apparatus such as a portable telephone, it is considered to provide openings for emitting a voice from a speaker on both the front face and backside of a housing of the portable telephone so that the voice from the speaker can be heard whether a folding type portable telephone is open or closed for instance.
Here, the speaker disclosed in Japanese Patent Laid-Open No. 2002-345084 is intended to emit the voice only to the front face side, and has a connector mounted on its backside so that its structure is not suited to emitting a voice from the backside.
To emit the voice from both the front face and backside, the speaker of an ordinary type having a lead connected thereto is adopted rather than the speaker of a special structure as disclosed in Japanese Patent Laid-Open No. 2002-345084, and the backside of the speaker is also used. As the speaker is constituted to produce a sound from the front face, the sound from the backside has a low sound pressure. Therefore, it is necessary to devise a method to emit the voice efficiently so that it can be heard at a sufficient volume from the backside. Here, the sound from the front face of the speaker and the sound from the backside of the speaker are mutually in opposite phases, and so they are mutually canceled to reduce the sound pressure consequently if a part of the sound from the front face of the speaker is emitted from the housing in concert with the sound from the backside of the speaker.